1. Field of the Invention
The present invention relates to a carrier tape for containing a small good such as chip size packages (hereinafter sometimes referred to as CSPs) for use in semiconductor devices and microphones for use in cellular phones, and a container using the carrier tape.
2. Discussion of the Related Art
In general, when chips for use in semiconductor devices are manufactured, the electric properties of the manufactured chips are checked in the final stage of the production process to determine whether the chips do not have a defect, and then only non-defective chips are packaged in a predetermined wrapper to be shipped. This operation is automatically performed now. When such chips are packaged, a method in which the chips are contained in each of recessed portions of an embossed tape (i.e., a carrier tape), which recessed portions are arranged in the longitudinal direction of the carrier tape at equal intervals. Then the recessed portions are covered with a cover tape, and thereby the chips are enclosed in the carrier tape.
FIGS. 11A and 11B are schematic views illustrating a conventional carrier tape. FIG. 11A is a plane view of the conventional carrier tape, and FIG. 11B is a cross sectional view of the conventional carrier tape when the carrier tape is cut at a line of B-B. A cover tape 12 is illustrated in FIG. 11B but is not illustrated in FIG. 11A.
Referring to FIGS. 11A and 11B, numeral 2 denotes a carrier tape which is typically made of a flexible resin. In the carrier tape 2, pockets 4 (i.e., embossed portions) are formed in the longitudinal direction of the carrier tape 2 to contain a good 6 such as CSPs therein. It is supposed that in this embodiment a CSP is contained in each of the pockets 4. The CSP 6 is contained in the pocket 4 such that the electrode terminals, such as solder terminals, of the CSP 6 face downward.
The pockets 4 are arranged at equal intervals in a line in the longitudinal direction of the carrier tape 2. In addition, holes 8 which are used for periodically feeding the carrier tape 2 are also formed at equal intervals in a line in the longitudinal direction of the carrier tape 2 such that the line of the holes 8 is parallel to the line of the pockets 4.
The flat surface of the carrier tape 2 on the side in which openings of the pockets 4 are formed serves as a flange portion 10. On the flange portion 10, the cover tape 12 is provided to seal the CSP 6 using an adhesive or a heat/pressure method.
The carrier tape 2 in which the CSP 6 is contained in the pockets 4 and is sealed with the cover tape 12 is reeled such that the cover tape 12 faces outward. FIG. 12 illustrates a cross section of a portion of the reeled carrier tape 12. Referring to FIG. 12, a pocket 4b is located right on another pocket 4a. In FIG. 12, the pocket 4a is located on an inner side of the reeled carrier tape. Numeral 38 denotes a good (a CSP in this case) contained in the pockets 4a and 4b. 
In general, the pockets 4 are formed such that the area of the outer surface of the bottom of the pockets 4 is smaller than the area of the opening of the pockets 4, in order that the CSPs 6 can be easily contained in or taken out of the pockets 4. Even when it is taken into consideration that the carrier tape 2 has a thickness, the area of the outer surface of the bottom of the pockets 4 is still smaller than that of the opening of the pockets 4. Therefore, when the pocket 4b is located right on the pocket 4a as illustrated in FIG. 12, the bottom portion of the upper pocket 4b invades the opening of the lower pocket 4a if a force is applied to the pockets 4a and 4b, for example, when the carrier tape 2 is reeled or the reeled carrier tape 2 is transported. This phenomenon is called “nesting”.
In this case, if the good 6 is a CSP having a BGA (Ball Grid Array) type solder terminal, the solder terminal is deformed due to the nesting. Goods other than the CSPs can be often damaged due to the nesting.
In attempting to prevent the nesting, Unexamined Japanese Patent Application 2002-046770 discloses a carrier tape in which the structure of the inner wall of the pockets is changed. In the carrier tape, a rib is formed on the pocket so as to extend outward. Since the size of the bottom of the pocket including the rib is larger than that of the opening thereof, the nesting problem can be prevented.
By using this technique, there is no problem when relatively large goods are contained in the carrier tape. However, when a small good such as CSPs is contained therein, the functionality of the carrier tape is deteriorated because the ribs which do not serve to support the good, have to be formed in the pockets.
Because of these reasons, a need exists for a carrier tape which can prevent the nesting without changing the pocket itself.